1. Field of the Invention
The present invention relates to a magnetic disk apparatus used in a computer system and including a plurality of coaxially arranged magnetic disks and a magnetic head assembly, and in more specifically, the present invention relates to an improved magnetic head assembly having a flexible printed circuit attached to a head carriage by an adhesive.
2. Description of the Related Art
A magnetic disk apparatus comprises a plurality of coaxially arranged magnetic disks and a magnetic head assembly for cooperation with the magnetic disks. The magnetic head assembly comprises a head carriage with a hub and head arms extending from the hub in a line so that each of the head arms is inserted between two adjacent magnetic disks. Each of the head arms has at the free end thereof two spring arms, and a magnetic head is carried by each of the spring arms for access to the respective surfaces of the magnetic disks. The head carriage is rotatably supported by a shaft via bearings and rotationally actuated by a moving-coil-type motor so that the magnetic heads can move radially over the magnetic disks.
A flexible printed circuit is attached to the side surface of the head carriage for transferring electrical signals between the magnetic heads and a signal processing device. The flexible printed circuit comprises an electrical pattern sandwiched between the first and second insulating films, and electrical components such as integrated circuits (ICs), resisters and capacitors. These electrical components are arranged for each of the head arms. The electrical pattern includes a plurality of conductive lines extending along each of the head arms. Four conductive lines extend along each of the head arms for two inductive type magnetic heads, and eight conductive lines extend along each of the head arms for magneto-resistive type magnetic heads.
Conventionally, the flexible printed circuit is adhered to the head carriage by a thermosetting adhesive, typically, an epoxy adhesive, for firmly fixing the flexible printed circuit to the movable head carriage.
In recent computer systems, there is an increasing demand for a high storing capacity in the magnetic disks. To enhance the recording density in the magnetic disks, it is necessary to improve a positioning capability of the magnetic heads relative to the tracks on the magnetic heads. In an attempt to improve a positioning capability of the magnetic heads, it has found that there is an occurrence of a slight off-track of the moving magnetic heads, in particular, the uppermost and the lowermost magnetic heads, when the flexible printed circuit is adhered to the head carriage by a thermosetting adhesive.